我正在尝试制作一个应用程序,在其中使用Recycle View和Volley从服务器获取数据,并且我还使用了Navigation抽屉和片段,一切正常,但当在recycle-view上没有数据时,我想显示一个通知,例如“没有数据!”我多次搜索互联网,但没有找到合适的解决方案,或者因为我完全是初学者,所以无法正确理解。
波纹管是我的Java文件
1.适配器
package com.eworld.myapplication;
import android.content.Context;
import android.support.annotation.NonNull;
import android.support.v7.widget.RecyclerView;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import com.squareup.picasso.Picasso;
import java.util.List;
public class ExchangesAdapter extends RecyclerView.Adapter<ExchangesViewHolder> {
private List<ExchangesSetterGetter>exchangeList;
private Context context;
public ExchangesAdapter(List<ExchangesSetterGetter> exchangeList, Context context) {
this.exchangeList = exchangeList;
this.context = context;
}
@NonNull
@Override
public ExchangesViewHolder onCreateViewHolder(@NonNull ViewGroup viewGroup, int i) {
View view=LayoutInflater.from(viewGroup.getContext()).inflate(R.layout.cardlayout,viewGroup,false);
ExchangesViewHolder viewHolder=new ExchangesViewHolder(view);
return viewHolder;
}
@Override
public void onBindViewHolder(@NonNull ExchangesViewHolder exchangesViewHolder, int i) {
String status="";
final ExchangesSetterGetter exchangesPosition=exchangeList.get(i);
if (exchangesPosition.getStatus().equals("1")) {
status = "Awaiting Confirmation";
} else if (exchangesPosition.getStatus().equals("2")) {
status = "Awaiting Payment";
} else if (exchangesPosition.getStatus().equals("3")) {
status = "Processing";
} else if (exchangesPosition.getStatus().equals("4")) {
status = "proceed";
} else if (exchangesPosition.getStatus().equals("5")) {
status = "Timeout";
} else if (exchangesPosition.getStatus().equals("6")) {
status = "Denied";
} else if (exchangesPosition.getStatus().equals("7")) {
status = "Canceled";
} else if (exchangesPosition.getStatus().equals("8")) {
status = "Unknown";
}
exchangesViewHolder.gatewayFrom.setText(exchangesPosition.getAmountFrom() + " " + exchangesPosition.getCurrencyFrom() + " " + exchangesPosition.getExchangeFrom());
exchangesViewHolder.gatewayTo.setText(exchangesPosition.getAmountTo() + " " + exchangesPosition.getCurrencyTo() + " " + exchangesPosition.getExchangeTo());
exchangesViewHolder.status.setText(status);
Picasso.get().load("https://eworld.ltd/" + exchangesPosition.getImgSend()).into(exchangesViewHolder.imgSendFrom);
Picasso.get().load("https://eworld.ltd/" + exchangesPosition.getImgReceived()).into(exchangesViewHolder.imgSendTo);
}
@Override
public int getItemCount() {
return exchangeList.size();
}
}
2.查看架
package com.eworld.myapplication;
import android.support.annotation.NonNull;
import android.support.v7.widget.RecyclerView;
import android.view.View;
import android.widget.ImageView;
import android.widget.TextView;
public class ExchangesViewHolder extends RecyclerView.ViewHolder {
ImageView imgSendFrom,imgSendTo;
TextView gatewayFrom,gatewayTo,status;
public ExchangesViewHolder(@NonNull View itemView) {
super(itemView);
imgSendFrom=itemView.findViewById(R.id.img1);
imgSendTo=itemView.findViewById(R.id.img2);
gatewayFrom=itemView.findViewById(R.id.tv1);
gatewayTo=itemView.findViewById(R.id.tv2);
status=itemView.findViewById(R.id.tv3);
}
}
3.Getter and Setter(数据模型)
package com.eworld.myapplication;
public class ExchangesSetterGetter {
private String exchangeFrom,exchangeTo,status,imgSend,imgReceived,currencyFrom,currencyTo,amountFrom,amountTo;
public ExchangesSetterGetter(String exchangeFrom, String exchangeTo, String status, String imgSend, String imgReceived, String currencyFrom, String currencyTo, String amountFrom, String amountTo) {
this.exchangeFrom = exchangeFrom;
this.exchangeTo = exchangeTo;
this.status = status;
this.imgSend = imgSend;
this.imgReceived = imgReceived;
this.currencyFrom = currencyFrom;
this.currencyTo = currencyTo;
this.amountFrom = amountFrom;
this.amountTo = amountTo;
}
public String getCurrencyFrom() {
return currencyFrom;
}
public void setCurrencyFrom(String currencyFrom) {
this.currencyFrom = currencyFrom;
}
public String getCurrencyTo() {
return currencyTo;
}
public void setCurrencyTo(String currencyTo) {
this.currencyTo = currencyTo;
}
public String getAmountFrom() {
return amountFrom;
}
public void setAmountFrom(String amountFrom) {
this.amountFrom = amountFrom;
}
public String getAmountTo() {
return amountTo;
}
public void setAmountTo(String amountTo) {
this.amountTo = amountTo;
}
public String getExchangeFrom() {
return exchangeFrom;
}
public void setExchangeFrom(String exchangeFrom) {
this.exchangeFrom = exchangeFrom;
}
public String getExchangeTo() {
return exchangeTo;
}
public void setExchangeTo(String exchangeTo) {
this.exchangeTo = exchangeTo;
}
public String getStatus() {
return status;
}
public void setStatus(String status) {
this.status = status;
}
public String getImgSend() {
return imgSend;
}
public void setImgSend(String imgSend) {
this.imgSend = imgSend;
}
public String getImgReceived() {
return imgReceived;
}
public void setImgReceived(String imgReceived) {
this.imgReceived = imgReceived;
}
}
4.最后是我的带有回收视图的片段活动
package com.eworld.myapplication;
import android.os.Bundle;
import android.support.annotation.NonNull;
import android.support.annotation.Nullable;
import android.support.v4.app.Fragment;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Toast;
import com.android.volley.Request;
import com.android.volley.RequestQueue;
import com.android.volley.Response;
import com.android.volley.VolleyError;
import com.android.volley.toolbox.StringRequest;
import com.android.volley.toolbox.Volley;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import java.util.ArrayList;
import java.util.List;
public class ExchangesFrag extends Fragment {
RecyclerView recyclerView;
ExchangesAdapter adapter;
List<ExchangesSetterGetter> listItems;
SharedPrefManager sharedPreferences;
int uid;
@Nullable
@Override
public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
View exchanges=inflater.inflate(R.layout.exchanges_layout,container,false);
recyclerView=exchanges.findViewById(R.id.rview);
recyclerView.setHasFixedSize(true);
recyclerView.setLayoutManager(new LinearLayoutManager(getActivity()));
listItems=new ArrayList<>();
sharedPreferences=new SharedPrefManager(getActivity());
uid = sharedPreferences.getUser().getId();
loadData();
return exchanges;
}
public void loadData() {
StringRequest stringRequest=new StringRequest(Request.Method.GET, URLs.url+uid, new Response.Listener<String>() {
@Override
public void onResponse(String response) {
try {
JSONObject jsonObject = new JSONObject(response);
JSONArray jsonArray = jsonObject.getJSONArray("data");
for (int i = 0; i < jsonArray.length(); i++) {
JSONObject receive = jsonArray.getJSONObject(i);
ExchangesSetterGetter exchangesSetterGetter = new ExchangesSetterGetter(
receive.getString("exchangeFrom"),
receive.getString("exchangeTo"),
receive.getString("status"),
receive.getString("imgSend"),
receive.getString("imgReceive"),
receive.getString("sendCurrency"),
receive.getString("receiveCurrency"),
receive.getString("amount_send"),
receive.getString("amount_receive")
);
listItems.add(exchangesSetterGetter);
}
adapter = new ExchangesAdapter(listItems, getContext());
recyclerView.setAdapter(adapter);
} catch(JSONException e){
e.printStackTrace();
}
}
}, new Response.ErrorListener() {
@Override
public void onErrorResponse(VolleyError error) {
Toast.makeText(getContext(),"error on volley",Toast.LENGTH_LONG).show();
}
});
RequestQueue queue= Volley.newRequestQueue(getContext());
queue.add(stringRequest);
}
}
最佳答案
在片段xml中添加一个额外的textview
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<TextView
android:id="@+id/tv_no_data"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_centerInParent="true"
android:textSize="22sp"
android:visibility="gone" />
<android.support.v7.widget.RecyclerView
android:id="@+id/rv_ride_list"
android:layout_width="match_parent"
android:layout_height="match_parent" />
</RelativeLayout>
然后在你的活动中
JSONArray jsonArray = jsonObject.getJSONArray("data");
if(jsonArray.length() > 0){
//process data and initialize adapter
}else{
//Set Text view visible
}